Abstract
Pollen grains and spores in moss polsters are compared with vegetation along transects across vegetational gradients in a large peatland in northern Minnesota. The distribution, percentage values, and source of 135 pollen and spore types are traced and related to the broad—scale vegetation pattern in the midwestern United States, and to the fine—scale vegetation pattern in the peatland. The pollen assemblages of taxa presently not growing in the peatland constitute the regional pollen deposition, with nearly constant proportions of pollen types distributed across the study area. Regional pollen values are compared for several peatlands in northern Minnesota and with the regional forest composition. The fine—scale pattern of peatland vegetation types corresponds well with the spatial pattern of the local pollen assemblages. Peatland vegetation types are characterized on the basis of these pollen assemblages. Conclusions on development of peatland vegetation can be drawn from local pollen assemblages preserved in sediment cores. Pollen transport for wind—pollinated Abies, Pinus, Betula, Alnus, Fraxinus, and Typha is discernible in the peatland only within 200 m from their source in local plant populations. The dispersal pattern of Abies pollen from an Abies balsamifera stand is related to wind speed and direction and sky cover for as much as 5 yr preceding sample collection. Most peatland pollen types are restricted in distribution to their corresponding vegetation types.
Published Version
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